Overindulges and goes off booty (6)
I believe the answer is:
spoils
'booty' is the definition.
(both can mean the proceeds or prize from something)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for spoils that I've seen before include "Mars the loot" , "pillage" , "Cossets, fails to instil discipline into" , "Damages" , "Booty" .)